<?php 

/**
*+----------------------------------------------------------
* 字符串截取，支持中文和其他编码
*+----------------------------------------------------------
* @static
* @access public
*+----------------------------------------------------------

* @param string $str 需要转换的字符串
* @param string $start 开始位置
* @param string $length 截取长度
* @param string $charset 编码格式
* @param string $suffix 截断显示字符
*+----------------------------------------------------------
* @return string
*+----------------------------------------------------------

*/

function msubstr($str, $start=0, $length, $charset="utf-8", $suffix=true){

	if(function_exists("mb_substr")){

		if($suffix){

			return mb_substr($str, $start, $length, $charset)."...";

		}else{

			return mb_substr($str, $start, $length, $charset);

		}

	}elseif(function_exists('iconv_substr')) {

		if($suffix){

			return iconv_substr($str,$start,$length,$charset)."...";

		}else{

			return iconv_substr($str,$start,$length,$charset);

		}

	}

	$re['utf-8']   = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|[\xe0-\xef][\x80-\xbf]{2}|[\xf0-\xff][\x80-\xbf]{3}/";

	$re['gb2312'] = "/[\x01-\x7f]|[\xb0-\xf7][\xa0-\xfe]/";

	$re['gbk']    = "/[\x01-\x7f]|[\x81-\xfe][\x40-\xfe]/";

	$re['big5']   = "/[\x01-\x7f]|[\x81-\xfe]([\x40-\x7e]|\xa1-\xfe])/";

	preg_match_all($re[$charset], $str, $match);

	$slice = join("",array_slice($match[0], $start, $length));

	if($suffix){

		return $slice."...";

	}else{

		return $slice;

	}

}

?>